The packaging of different products in expanded polystyrene containers or the like is increasingly frequent, especially for perishable products, due to the preservation conditions which this type of containers can offer. The containers are generally obtained in the form of trays by means of shaping installations and are supplied to the packager, who will carry out the operation of filling and closing the container. This system involves a series of drawbacks, such as the need for the packager to transport and store the containers, having to adapt to beverage containers offered by the container manufacturer, the possibility of contamination of the container from its manufacture to its filling and closing, etc.
To solve this drawback, application PCT WO 2005/030471 describes a machine which allows continuously shaping the container, from an expanded polymer web, filling the container and closing and supplying it for its sale.
The machine is formed by an assembly of reel-carrier axes and an unwinding unit for unwinding the expanded polymer web, a preheating unit for preheating the web, a molding unit in which the containers are shaped, a closing and sealing unit for closing and sealing the containers, printing units, a lengthways cutting unit and another crossways cutting unit. The machine is completed with a drag system for dragging the sheet, which system stops the forward movement of said sheet while the different operations in the different stations are being carried out, and causes the forward movement thereof once these operations have ended.
Although this machine provides for the manufacture of containers, the filling and closing thereof, all of this in a continuous manner, it has certain drawbacks, fundamentally in the constitution and operation of the preheating station, the thermoforming station and the closing station for the containers.
The preheating station does not allow suitable regulation of the preheating temperature according to the speed or rate of movement of the web along the different stations.
The thermoforming station has the risks of unwanted deformations occurring in the wall of the container.
As regards the sealing station, the manner in which this operation is carried out, after the creation of an inert atmosphere inside the container ensuring the preservation of the contained product, is not provided.
With respect to the cutting stations, since two cutting stations, a lengthways cutting station and another crossways cutting station are arranged consecutively, the length of the machine increases the cost thereof.